Cut the chicken breast into small cubes and season with salt and pepper.
In a large bowl, mix together the flour, baking powder, milk and egg until fully combined.
Add the marinade ingredients – garlic, ginger, brown sugar, soy sauce – to the chicken pieces and toss until evenly coated.
Dredge each chicken piece in the flour mixture, shaking off any excess.
Heat oil in a large skillet over medium-high heat and add the chicken pieces. Fry until golden brown on both sides and cook through, about 5 minutes per side.
Transfer to a paper towel-lined plate and let cool slightly before serving.